The primary air polluting emissions usually produced by turbines burning conventional hydrocarbon fuels are oxides of nitrogen, carbon monoxide and unburned hydrocarbons. It is well known in the art that oxidation of molecular nitrogen in air breathing engines is highly dependent upon the maximum temperature in the combustion system reaction zone and the residence time for the reactants at the maximum temperatures reached within the combustor. The level of thermal NOx formation is minimized by maintaining the reaction zone temperature below the level at which thermal NOx is formed or by maintaining an extremely short residence time at high temperature such that there is insufficient time for the NOx formation reactions to progress.
Hot combustion gas is exhausted from a combustor to a first stage vanes and blades of a turbine. In conventional systems, the use of first stage vanes to accelerate and turn gas flow presents several challenges. The vanes and associated vane support structure need high strength characteristics to withstand the forces generated in changing the direction of the hot gas flow over an angle in a relatively short distance. The temperature of gas flow and heat generated by a gas flow turning process require a cooling system. The forces and heat generated may crack the vanes and associated support structure. In such systems, the turbine firing temperature within the combustor may be affected or as such may require complex cooling requirements.